Why conductivity check is so important in purified water quality testing?
Conductivity is the ability of a material to pass an electric current. Since the charge on ions in solution facilitates the conductance of electrical current, the conductivity of the solution is proportional to its ion concentration.
Conductivity in water is affected by the presence of inorganic dissolved solids such as chloride, nitrate, sulfate, and phosphate anions (ions that carry a negative charge) or sodium, magnesium, calcium, iron, and aluminum cations (ions that carry a positive charge). Organic compounds like oil, phenol, alcohol, and sugar do not conduct electrical current very well and therefore have a low conductivity when in water. Conductivity is also affected by temperature: the warmer the water, the higher the conductivity. For this reason, conductivity is reported as conductivity at 25 degrees Celsius.
The basic unit of measurement of conductivity is the mho or siemens. Conductivity is measured in micromhos per centimeter (µmhos/cm) or microsiemens per centimeter (µs/cm). Distilled water has a conductivity in the range of 0.5 to 3 µmhos/cm.
Water purity can be quickly estimated on the basis of electrical conductivity or resistance — very pure water conducts electricity poorly, because the electrical current is transported by the ions in solution, in other words conductivity increases as the concentration of ions increases.
Factors which determine the degree of water conductivity includes
1.Concentration or number of ions
2.Mobility of the ion
3.Oxidation state (Valence)
4.Temperature of the water.